Intraventricular Meningioma Resection with Postoperative Ischemia of the Lateral Geniculate Nucleus

Accepted Manuscript Intraventricular Meningioma Resection with Post-Operative Ischemia of the Lateral Geniculate Nucleus Saman Sizdahkhani, MS, Stephen T. Magill, MD, PhD, Michael W. McDermott, MD PII:

S1878-8750(17)31167-1

DOI:

10.1016/j.wneu.2017.07.067

Reference:

WNEU 6129

To appear in:

World Neurosurgery

Received Date: 26 February 2017 Revised Date:

11 July 2017

Accepted Date: 12 July 2017

Please cite this article as: Sizdahkhani S, Magill ST, McDermott MW, Intraventricular Meningioma Resection with Post-Operative Ischemia of the Lateral Geniculate Nucleus, World Neurosurgery (2017), doi: 10.1016/j.wneu.2017.07.067. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT Intraventricular Meningioma Resection and LGN Ischemia 1

Title: Intraventricular Meningioma Resection with Post-Operative Ischemia of the Lateral

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Geniculate Nucleus

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Saman Sizdahkhani MS,1 Stephen T. Magill MD, PhD,2 Michael W. McDermott MD2

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North Chicago, IL, USA

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San Francisco, CA, USA

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Department of Neurological Surgery, University of California

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Disclosure of Funding: This research did not receive specific grant from funding agencies in the public,

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commercial, or not-for-profit sectors.

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Disclosure of Financial Support or Industry Affiliation: None

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Please address correspondence to:

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Stephen T. Magill, MD, PhD

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Department of Neurological Surgery

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University of California, San Francisco

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505 Parnassus Ave. Room M779

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San Francisco, CA 94143-0112

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Phone: 415-353-3904, Fax: 415-353-3907

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E-mail: [email protected]

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Chicago Medical School at Rosalind Franklin University

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Key words: Meningioma, Complication, Intraventricular, Lateral Geniculate, Ischemia

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Running title: Intraventicular Meningioma Resection and LGN Ischemia

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Abbreviations: IVM, intraventricular meningiomas; LGN, lateral geniculate nucleus; MRI, magnetic

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resonance imaging; DTI, diffusion tensor imaging; DWI, diffusion weighted image; AChA, anterior

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choroidal artery; LPChA, lateral posterior choroidal artery.

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Abstract:

27 Background: Intraventricular meningiomas (IVMs) comprise 0.5-3% of intracranial meningiomas. They

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often cause obstructive hydrocephalus and are commonly treated with surgical resection or stereotactic

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radiosurgery.

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Objective: To describe the surgical approaches and resection techniques needed to approach

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intraventricular tumors, while highlighting the eloquent anatomy and blood supply surrounding the

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ventricular system in order to avoid neurological injury.

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Methods: Two cases of left atrial IVMs that were complicated by postoperative lateral geniculate nucleus

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(LGN) ischemia and resultant temporary contralateral quadrantanopia are described. The safe surgical

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approaches to the atrium of lateral ventricles as well as the anatomy and blood supply to the LGN and

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optic radiation are discussed and illustrated.

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Results: In both cases, the patients had complete resection of their tumors. They both ultimately made a

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good recovery after transient visual deficits. These cases provide useful demonstrations of eloquent

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anatomy of the ventricular walls and visual pathway anatomy.

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Conclusion: Care must be taken to avoid visual pathways along the lateral ventricle wall and the nearby

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arterial supply of the lateral geniculate nucleus from the choroidal arteries when resecting intraventricular

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tumors.

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Introduction:

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Patients with intraventricular meningiomas (IVMs) often present with symptoms secondary to obstructive hydrocephalus or mass effect from a trapped lateral ventricle1,2. IVMs account for 0.5-3% of

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meningiomas3,4. Although the majority of IVMs occur within the atrium of the lateral ventricle (80%)

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they also may originate from the third (15%) and fourth ventricle (5%)1,3. Treatment options include

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radiosurgery or surgical resection5.

Depending on tumor depth, within the ventricular system, IVMs can be located adjacent to

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arteries that supply eloquent white matter pathways or cortical structures. Therefore, surgical resection is

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often technically challenging6. Various surgical approaches can be used to access the ventricular system

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and the surgeon should tailor his plan to individual patients, taking into account the tumor location,

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handedness and other clinical factors to optimize safety6,7.

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Here we report two patients with lateral ventricle IVMs that resulted in lateral geniculate nucleus (LGN) ischemia after surgical resection via a parieto-occipital transcortical approach through the occipital

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horn of the lateral ventricle. A brief overview of the neurosurgical approaches to the lateral ventricular

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atrium is followed by the anatomy and blood supply of the LGN and the trajectory of the optic radiations.

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Materials and Methods:

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This is a retrospective review of two cases. The electronic medical record and radiology were reviewed

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for both cases. The institutional review board of the author’s university approved this study (IRB# 13-

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12587).

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Results:

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Case 1: A 34-year-old right-handed woman had a surfing accident, and, in addition to an orbital fracture,

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the head CT revealed an intra-ventricular mass. Contrast-enhanced magnetic resonance imaging (MRI)

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demonstrated a mass within the atrium of the left lateral ventricle with surrounding edema in the

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temporal, parietal and occipital lobes (Figure 1A, B). The left temporal horn and the occipital horn were

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ACCEPTED MANUSCRIPT Intraventricular Meningioma Resection and LGN Ischemia obstructed. The patient had been having daily morning left temporal headaches, which were often

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accompanied by dizziness, nausea and vomiting. She also had intermittent visual symptoms. These had

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been attributed to migraines, which were diagnosed 8 years prior. An MRI at that time was normal. On

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physical exam, the patient was neurologically intact, including full visual fields and normal ocular fundi.

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Her language and reading comprehension were also normal. She had no family history of meningioma,

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radiation, breast or thyroid tumors. She elected to undergo surgical resection of the tumor. A left parieto-

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occipital trans-cortical approach via the occipital horn was selected and performed as described below

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with a Simpson Grade 1 resection. Post-operatively the patient was neurologically intact except for a right

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inferior quadrantanopia. While the post-operative MRI showed a gross total resection of the tumor

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(Figure 1C), it also revealed a small infarct in the left LGN (Figure 1D). Final pathology was atypical

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meningioma, WHO grade II. At 6 months post-operative, her visual fields had recovered and her tumor

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had not recurred.

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Case 2: A 36-year-old male obtained a CT scan as part of an insurance screening and was incidentally

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found to have a left atrial mass. MRI demonstrated a 3 cm left atrial contrast enhancing mass consistent

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with meningioma (Figure 2A, B). The left occipital horn displayed slight dilation with some surrounding

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edema in the parietal lobe. He described generalized headaches for the past 6 months, especially while

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reading, but these were similar to migraines he had had since childhood. The patient’s neurological exam

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was normal, including full visual fields and normal ocular fundi as well as normal language and reading

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comprehension. He has no family history of meningioma, radiation, breast or thyroid tumors. He elected

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to under surgical resection of the tumor. A Simpson Grade 1 resection was performed via a left parieto-

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occipital transcortical approach via the occipital horn was described in detail below. Post-operatively he

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had a right homonymous hemianopsia. Post-operative MRI showed a gross total resection (Figure 2C, D)

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as well as a left LGN infarct (Figure 2E). Diffusion tensor imaging (DTI) based tractography showed that

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the infarct interrupted the left optic radiations at the LGN (Figure 2F). Final pathology was meningioma,

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WHO Grade 1. At three week follow up with Humphrey Visual Field tests, his right superior quadrant

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had recovered fully, but he still had a right inferior quadrantanopia. At four month follow up his vision

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and visual fields had returned to normal.

103 Operative Technique: The IVMs presented here were both located within the atrium of the left lateral

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ventricle and were resected via a left parieto-occipital transcortical transventricular approach via the

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occipital horn. Both patients were positioned laterally with the head secured with the Mayfield apparatus.

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Intraoperative stereotactic neuronavigation was used to map the tumor. A U-shaped skin incision was

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made and a occipital parietal craniotomy was performed with burr holes and a footplate drill attachment.

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The dura was incised in a U-shaped manner and reflected medially towards the superior sagittal sinus.

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Using the stereotactic neuro-navigation system, a vertically oriented paramedian occipital gyrus was selected with the shortest safe direct trajectory into the occipital horn of the lateral ventricle.

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Diffusion tensor imaging was used to project occipital visual fiber pathways on axial (as shown in Figure

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2F), and coronal MRI images at surgery. The pial surface of the superior occipital gyrus 2 cm lateral to

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the midline was then coagulated and opened with an 11-blade and straight microscissors. An image-

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guided stylet was used to position a catheter into the occipital horn of lateral ventricle. Blunt dissection

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with a Rhoton #4 dissector was used to follow the catheter down to the occipital horn of the lateral

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ventricle. Self-retaining retractors were placed along the tract.

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Using the operative microscope, the posterior margin of the tumor was identified. The surface of the tumor was coagulated in a rectangular fashion on its posterior surface and incised with straight

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microscissors. A sample was taken for biopsy. Both tumors were very fibrous. They were debulked

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internally with the ultrasonic aspirator and the carbon dioxide laser. Once adequately debulked, we

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dissected around the margins of the tumor, respecting the ependymal surface, and detaching it from the

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ventricular wall. The choroid plexus and choroidal artery were identified and the choroidal artery was

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coagulated where it was supplying the tumor. In both cases, there were multiple small vessels supplying

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the tumor that were coagulated and divided. An external ventricular drain was left in the cavity and the

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dura was repaired with interrupted sutures. The bone flap was repositioned and secured with titanium

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plates and screws prior to scalp closure.

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Surgical approaches to meningiomas in the atrium of the lateral ventricle

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The operative approach to IVMs depends on tumor location within the lateral ventricle and is beyond the

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scope of this article8. Here, we focus on a brief review of approaches to tumors within the atrium of the

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lateral ventricle and our surgical considerations for approach selection.

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Transtemporal Transcortical Approach: For meningiomas located in the posterior or middle temporal

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horn, or the atrium of the lateral ventricle, a transtemporal transcortical approach via the middle temporal

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gyrus provides the shortest trajectory and early access to the choroidal blood supply to the tumor. This

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approach can be used for meningiomas of the atrium in the non-dominant hemisphere. This approach

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should be avoided on the dominant hemisphere, as language centers within the posterior part of the

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middle temporal gyrus are at risk.

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A temporal craniotomy followed by a horizontal corticectomy along the posterior one-third of the middle temporal gyrus begins this approach. The transcortical path should be developed towards the

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tumor in the most direct manner possible. When taking this approach, one must also consider the eloquent

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fibers of the inferior loop of the optic radiations. We use the projected visual fiber pathways from axial

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and coronal reconstructed images to select the best trajectory on the image guidance system so as to avoid

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these fibers within the posterior temporal lobe and along the inferior aspect of the lateral wall of the

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atrium (Figure 3). In order to minimize damage, it is important to advance within a horizontal plane, with

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gentle retraction parallel to these fibers. Alternatively, one may avoid the optic radiations by beginning

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their approach along the inferior temporal gyrus and traversing around the fibers infero-medially towards

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the ventricle. This approach permits early coagulation of choroidal artery branches that may supply the

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tumor5.

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ACCEPTED MANUSCRIPT Intraventricular Meningioma Resection and LGN Ischemia Posterior Interhemispheric Precuneal Approach: For IVMs located in the atrium, one may use the

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posterior interhemispheric precuneal approach. An occipital craniotomy on the side of the lesion is

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performed taking care to protect the torcula, sagittal, and transverse sinuses. Posterior interhemispheric

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dissection is followed by a precuneal corticectomy, just in front of the parieto-occipital sulcus. As this

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transcortical path is developed, the surgeon will reach the medial wall of the posterior atrium, behind the

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choroidal fissure. This provides an operative corridor to the atrium and aims to avoid as much eloquent

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occipital cortex as possible.

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Posterior Interhemispheric Transcallosal Approach: A lesion within the posterior aspect of the body of

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the lateral ventricle can be approached transcallosally. A parieto-occipital craniotomy is performed

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followed by dissection along the posterior longitudinal fissure through the posterior body or splenium of

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the corpus callosum. This dissection will open the ventricle at the posterior body or atrium, respectively.

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Parietal, Parieto-Occipital, and Occipital Transcortical Approach: A parietal, parieto-occipital, or

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occipital craniotomy and transcortical approach can provide access to IVMs within the body, atrium, or

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occipital horn of the lateral ventricle, respectively. These approaches are grouped together as they are

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similar in their transcortical trajectories.

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For the parietal approach, a paramedian corticectomy is made posterior to the postcentral gyrus. The subcortical trajectory should provide the shortest route to the tumor, taking care to avoid the optic

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radiations. A parieto-occipital or occipital approach also utilizes a paramedian corticectomy, but located

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more posteriorly. A horizontally oriented paramedian corticectomy in the superior occipital gyrus can

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provide direct access to the occipital horn.

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Approaches through the superior or inferior parietal lobule of the dominant hemisphere may lead

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to dyslexia, agraphia, finger agnosia, acalculia, and visual field deficits. In the non-dominant hemisphere,

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hemi-special neglect and visual field deficits may occur. With a purely occipital approach only visual

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fiber pathways and visual deficits are at risk. Using image guidance and visual fiber pathway projections,

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a trajectory into the superior part of the occipital horn can minimize the risk of visual fiber damage.

180 Approach Selection: There is no single “ideal” approach to tumors in the atrium. Our approach selection

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is based on multiple factors. Our first consideration is whether the tumor is in the dominant or non-

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dominant hemisphere. For non-dominant tumors, we typically take a transcortical transtemporal approach

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to get to the atrium (Figure 3B). One problem with the transcortical transtemporal approach is that the

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visual fibers from Meyer’s loop run on the inferior and lateral wall of the atrium (Figure 3A). The advent

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of diffusion tensor imaging and fiber tracking now allows the surgeon easy visualization of the pathways

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and can assist with planning of the approach and entry site. These visual fibers are best seen in the coronal

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plane. If a more anterior approach is taken, the surgeon can angle posteriorly and avoid the visual fiber

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pathways (Figure 3B). The transcortical transtemporal approach gives the surgeon early access to control

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the choroidal arterial blood supply. However, even with early control of choroidal blood supply, big

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tumors often develop arterial supply off local perforators, and care must be taken during resection not to

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injure perforators, which can lead to LGN infarct, as happened in the cases presented. For tumors on the

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dominant hemisphere, this approach would require speech mapping, and thus, we typically select a

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parieto-occipital approach, as shown in the case examples. The parieto-occipital approach keeps the

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surgeon away from eloquent cortex, but has the disadvantage of not gaining access to the choroidal blood

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supply until later in the dissection. The senior author rarely uses the interhemispheric approaches, as they

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are far from the choroidal blood supply and are less conducive to tumor dissection in our hands. Finally,

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we now routinely use diffusion weighted imaging with tractography on our post-operative scans to

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monitor for small local injuries, which may have been missed before we included those protocols and

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sequences.

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Anatomy and Blood Supply of the Lateral Geniculate Nucleus

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The LGN is located within the posterolateral thalamus and receives bilateral visual information from the

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optic tract. The LGN has a dual blood supply from the anterior choroidal artery and the lateral posterior

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choroidal artery (Figure 4)9. The choroidal arteries supply the choroid plexus and provide branches to

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nearby neural structures as they pass along the choroidal fissure. Frequent sites of anastomoses occur

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between the anterior and lateral posterior choroidal artery throughout the choroid plexus. The anterior choroidal artery branches off the internal carotid artery where it navigates posteriorly

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to the middle incisural space and through the choroidal fissure, after which it courses posteriorly and

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dorsally beside the plexus. The lateral posterior choroidal artery branches from the posterior cerebral

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artery as it traverses within the ambient and quadrigeminal cisterns; it then passes around the pulvinar

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laterally. It travels through the choroidal fissure at the level of the body of the fornix so that it can feed the

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choroid plexus within the temporal horn, atrium and body10.

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Anatomy of the Optic Radiation

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Originating from the LGN, the optic radiations course along the margins of the ventricular system to

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reach the primary visual cortex along the calcarine sulcus. The fibers are divided into three groups:

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anterior, central, and posterior. The anterior fibers, which carry information from the upper half of the

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visual field, traverse superior and anterior to the temporal horn of the lateral ventricle; this anterior

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portion of the radiation is also known as Meyer’s loop. As the fibers traverse laterally and inferiorly to the

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atrium and occipital horn they terminate within the lower lip of the calcarine fissure. The central fibers

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serve the macula and course along the roof of the temporal horn towards the lateral wall of the atrium and

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occipital horn prior to terminating along the calcarine fissure. The posterior fibers carry information from

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the inferior visual field and travel directly from the LGN to the superior lip of the calcarine fissure along

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the lateral wall of the atrium and occipital horn of the ventricle10.

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Conclusions:

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We present two cases of atrial IVMs where surgical resection resulted in LGN ischemia with contralateral

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quadrantanopia. Both patients had excellent recovery of their vision several months postoperatively. The

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blood supply to the LGN comes from terminal branches of both the anterior choroidal artery and posterior

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ACCEPTED MANUSCRIPT Intraventricular Meningioma Resection and LGN Ischemia choroidal artery. Great care should be taken when resecting IVMs due to the eloquent neuroanatomy and

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vasculature within the operative corridor and adjacent to the ventricles. With large tumors the anterior

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margin of the tumor may be adjacent to the take off from choroidal arteries to the LGN so the surgeon

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should always coagulate vessels supplying the tumor as close to the capsule of the tumor as possible.

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235 236 Acknowledgements:

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The authors would like to thank Kenneth X. Probst for creating the illustration in Figure 3.

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References:

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doi:10.1016/j.surneu.2005.09.033.

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Figure 1: Case 1 Imaging: A) Pre-operative post-contrast T1 weighted MRI shows the left atrial mass.

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B) FLAIR imaging showing surrounding peri-tumoral edema. C) Post-operative post-contrast T1 MRI

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shows gross total resection of the tumor. D) Post-operative diffusion weighted imaging (DWI) shows an

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infarct in the superficial left LGN.

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Figure 2: Case 2 Imaging: A) Axial, and B) Coronal pre-operative post-contrast T1 weighted MRI

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shows the intraventricular tumor. C) Axial, and D) Coronal post-operative post-contrast T1 weighted MRI

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shows gross total resection of the tumor. E) Axial DWI images showing a left LGN infarction. F) Post-

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contrast T1 weighted MRI with diffusion tensor imaging (DTI) tractography overlay showing a disruption

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in the left optic radiations at the region of the infarct (arrow).

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Figure 3: Intraoperative navigation images showing transcortical transtemporal approach to the

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right (non-dominant) atrium. A) Axial (left) and coronal (right) FLAIR (upper) and T2 (lower)

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weighted MR diffusion tensor imaging fiber tractography study showing the relationship between tumors

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in the atrium and the optic radiations (turquoise), which pass along the inferior and lateral border of the

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ventricle. B) Axial (upper left), coronal (upper right), inline/trajectory view 1 (lower left), and

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inline/trajectory view 2 (lower right), post-contrast T1 weighted MRI showing the transtemporal

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transcortical approach trajectory to tumors in the right atrium. Fiber tracts are labeled as follows:

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turquoise = optic radiations; red = motor/corticospinal; green/yellow = arcuate fasciculus/association

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fibers; blue = inferior frontal occipital fasiculus; purple/pink = magnetic source imaging for unrelated

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magnetoencephalography study.

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Figure 4: Illustration demonstrating blood supply to the LGN. The anterior choroidal artery (AChA)

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branches from the internal carotid artery and supplies the choroid plexus. The lateral posterior choroidal

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artery (LPChA) branches from the P2 segment of the posterior cerebral arteries and also supplies the

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choroid plexus, where it anastomoses with branches of the AChA. Terminal branches from both the

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AChA and LPChA supply the LGN.

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ACCEPTED MANUSCRIPT Sizdahkhani et al. Intraventricular Meningioma Resection and LGN Ischemia 1

Highlights •

Intraventricular tumors often lie adjacent to the lateral geniculate nucleus.

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Choroidal arteries that supply tumors also supply nuclei near the ventricular wall.

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Tumor blood vessels must be coagulated as close to the tumor capsule as possible.

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ACCEPTED MANUSCRIPT Sizdahkhani et al. Intraventricular Meningioma Resection and LGN Ischemia Title: Intraventricular Meningioma Resection with Post-Operative Ischemia of the Lateral

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Geniculate Nucleus

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Saman Sizdahkhani MS,1 Stephen T. Magill MD, PhD,2 Michael W. McDermott MD2

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North Chicago, IL, USA

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San Francisco, CA, USA

Chicago Medical School at Rosalind Franklin University

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Department of Neurological Surgery, University of California

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Abbreviations: IVM, intraventricular meningiomas; LGN, lateral geniculate nucleus; MRI, magnetic

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resonance imaging; DTI, diffusion tensor imaging; DWI, diffusion weighted image; AChA, anterior

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